The embassy said that in response to the information, it was restricting American employees and their dependants from visiting housing compounds in the capital Riyadh at night.
"Confirmed information indicates that the Seder Village housing compound in Riyadh has been under active surveillance by terrorist elements," the embassy said in a statement.
"Other Western compounds in the kingdom may also be targeted," the statement added.
The US warning comes three days after Britain reminded its 30,000 nationals in Saudi Arabia that militants might be in the final phases of planning attacks in the kingdom.
Last month, two Saudi suicide bombers killed at least 18 people, mainly Arab expatriates, at a Riyadh housing compound.
"The Seder Village housing compound in Riyadh has been under active surveillance by terrorist elements"
US embassy in Saudi
On 12 May, the triple suicide bombing of three other housing complexes killed at least 35 people, including Americans and
Saudi officials said last week they had foiled an even bigger attack in Riyadh when security forces found a car loaded with over 1.2 tonnes of explosives.Another 1.3 tonnes of explosives were found nearby.
Saudi Arabia has cracked down hard on militants since the May attacks.